Heat Stroke in dogs — the harsh side of summer

For most humans summer means fun—shedding layers of clothing to venture outside and feel the warmth of the sun on our bodies. Our pets are unable to remove their furry coats and extreme summer heat can be extremely uncomfortable and even dangerous. 

We have all endured the cold and now is the time to enjoy having fun outdoors with our best furry friends. While this warmth brings us so much joy, high temperatures result in internal regulatory mechanism failure and subsequent heat stroke. If unattended this condition can be fatal.

Dogs have a limited number of coping mechanisms to control their temperature. Mammals are homeothermic (warm-blooded) which means they are normally able to control their internal temperature despite changes in the environment.

What is heat stroke? How can we identify the early signs and act before the emergency vet visit?

How do dogs control their temperature?

The first and most obvious sign that your dog is feeling the heat is panting — the primary regulatory mechanism. This may not alarm you as it is normal dog behaviour on exertion. By rapidly moving air around the mouth, nose and upper respiratory tract, evaporation cools the internal surfaces and in turn the blood flowing through the underlying vessels.  This process is hampered in brachycephalic breeds like pugs and bulldogs as the surface area available for cooling is much smaller than in the longer nosed dogs.

Sweat glands located in the underside of the paws are employed to moisten the hairless surface and cool by evaporation although in hotter weather this is not as successful in cooling the body as panting. 

As the dog heats up, the blood vessels in the nose and ears dilate and pump more blood closer to the surface in order to cool the animal’s body down.

In extreme heat dogs will naturally seek out cooler places. They lie on tiles and can dig into the earth under the shade to expose their bellies to the cool soil. Those that love water will swim or lie in a shallow pool. 

Consider that a fever in dogs is 40°C (pyrexia). It only takes another degree or two to be fatal.  Extreme environmental temperature or even excessive exercise on a moderately hot day can send your dog’s temperature skywards. Closing a dog in a hot car or even leaving them in a yard without shade or water can do the same. Obesity and prolonged seizures can also lead to a rise in temperature.

Some long-haired breeds have multiple layers of fur that in the hotter months act as insulators which trap a layer of cool air close to the skin.

Dogs that have double coats—a soft inner layer and an outer guard coat—are Golden Retrievers, Labradors, Border collies, Pomeranians, Chows, German shepherds, Huskies, Malamutes, Bernese mountain dogs, Akitas, Newfoundlands, Samoyeds and Australian shepherds. Here are a couple of good reasons not to shave these breeds in the summertime:

The soft undercoat traps cool air and the guard coat acts to shade the skin.  Shaving these breeds causes the undercoat to grow back more densely and disrupts the ability to trap cool air.

It is wiser to brush out the coat of these breeds in summer to help thin the undercoat and stimulate the natural oils present in the skin.

Dogs that can be shaved are Poodles, Yorkshire terriers and Shih-Tzus. But a reputable groomer will always keep at least an inch of hair to protect the skin.

What is the physiology of heat stroke?

Without getting too ‘scientific journal’ in this article, a vet nurse needs to be able to explain heat stroke in terms that most pet owners can understand.

Initially the heart rate rises, the spleen and the blood vessels in major organs all contract.  The reason for this is to distribute more blood to the surface of the body. 70% of the total body heat is dissipated through radiation and convection from the body surface.  When radiation of the heat from the skin diminishes, panting becomes the primary method of cooling.  Increased salivation moistens the airway to further assist with evaporation.

If the body is unable to dissipate the heat there is a drop in blood pressure.  This is due to most of the blood pooling close to the skin in order to cool down and subsequently not being available to the major organs.

The excessive heat damages muscle cells causing intracellular material to be discharged into circulation. This causes the blood to become acidic. The body’s inflammatory response to circulating toxins is to causes swelling in affected tissue. These are only some of the physiological results from internal tissue damage due to heat. All of the organs are affected by the drop in blood pressure, increase in toxins and subsequent swelling of tissue including the kidney, pancreas, brain, liver. Death from heat stroke is due to an overall collapse of all systems in the body.

What are the first signs of heat stroke?

Based on the horrific sequence above, we need to act quickly to identify the early signs of heat stress and prevent total collapse. Remember that heat stroke is a medical emergency and it is advised to take your dog to a vet immediately.

Here are some of the ways you can identify the primary signs of heat stress in your dogs

1. Excessive salivation and increased respiration

2. Colour changes in gums from deep pink to very pale

3. Dry and sticky gums

4. Lethargy: the dog is lying on his/her side and is unwilling to get up

5. Confusion/disorientation

6. Vomiting/diarrhoea

7. More serious signs are seizures and unresponsive collapse

If you have not identified a problem and acted by point 4 your dog will be in fatal danger.

Practical ways to prevent pandemonium

Firstly, stay calm. Your dog will be experiencing discomfort and fear. Your calm attitude will go a long way to reassure them.

Offer fresh, cold water to drink. If there is an air-conditioned car around, place the dog in the back so they can lie flat. If not, move them onto a cool surface in the shade and use a large flat object to fan them. Wet fabric like towels or clothing can be placed inside the groin and on their paws and ears. Replace the fabric regularly as it will be absorbing the heat. Do not use ice. Do not pour water into the dog’s mouth. 

It is advisable to get them to a vet as soon as possible to try and prevent further damage to their organs. If this is not possible, reducing the temperature to around 38-39 °C is vital.  If the gums do not return to a pink colour within 20 minutes, the internal organ complications can lead to death.

Here are some useful items to carry with you on hot days when exercising your dog.

1. Plenty of water

2. A bowl

3. A towel

4. A cheap thermometer

5. A rigid piece of cardboard or plastic as a fan

Another way to prevent heat stroke in dogs is simply to stay away from excessive exercise on a hot day. Talliwags Wellness World is a cool indoor space that is just perfect for those hot Cape Town summer days!

Remember that your dogs have a layer of ‘clothing’ that they are unable to remove when they get hot. If the environment is too hot for you then it is more than too hot for them.

©Liz Roodt – 2025